A strange problem with rendering glass in Cycles
After pressing random buttons, and trying to fix mesh - successfully i did it!
There was problem with my mesh - gaps caused mirror modifier, and some other things. 

There is how I fixed it:

At first I was searching for something wired in mesh, found not connected edges, so I selected them.

And scaled them down. pressed s + x (axis of scaling) + entered 0 on keyboard


After scaling them together i removed doubles by selecting all edges press two times a then click w > Remove Doubles



In the end, with selected mesh I pressed Mesh>Clean up>Split Concave Faces...


And Voilà!


 :)